Hello, sorry for having trouble with paypal. Maybe it can be some kind of region issue but I have not sure yet.
In fact I don't know the real issue. I just know I can pay other packs on itch using guest checkout without login if I met that issue, but when I pay your pack there is no that option( Pay with Credit or Debit Card ), Only Login or Create an Account. I will be appreciated if you can turn on that option temporarily I will be able to pay your pack. I will pay it as soon as possible, Then you can turn it off.
I found a similar issue in the itch io forum, https://itch.io/t/4539781/how-to-avoid-mandatory-paypal-registration-when-buying you can follow the steps and try to fix this issue.